Effect of Titanium Content and Mechanical Activation on Ni–Al–Ti Combustion
Н. А. Кочетов
Abstract
This paper describes the effect of preliminary mechanical activation (MA) and Ti content on maximum temperature, maximum burning rate, composite particle size, mixture yield after MA, sample elongation during combustion, and the phase composition and morphology of combustion products in the Ni–Ti–Al system. The preliminary MA of a Ni + Al + Ti mixture expands the limit of titanium content at which samples can burn without preheating, from 17 to 59% (by weight). Mechanical activation is followed by a drop in the number of phases in the products and an increase in the burning rate, while the maximum synthesis temperature decreases. The augmentation of the Ti content in the Ni + Al + Ti mixture reduces the burning rate and maximum combustion temperature of both initial and mechanically activated mixtures. Moreover, as the titanium content increases, the average size of composite particles decreases and the yield of the activated mixture becomes larger. In the combustion of mechanically activated mixtures with a high (24–52%) titanium content, the Ti2Ni phase and the Ni2TiAl Heusler phase predominate in the products, while the traces of melting are visually observed. In the activated Ni + Al + Ti mixture, the Ti content at which the Heusler phase content in the combustion products becomes maximum is revealed. Most of the observed dependences are explained.